Production of high temperature, high performance, and high energy hydrocarbon fuels



3,067,126 E, AND

A. M. LEAS EMPERA Dec. 4, 1962 PRODUCTION OF HIGH T TURE, HIGHPERFORMANC HIGH ENERGY HYDROCARBON FUELS Filed Aug. 6, 1959 UrESOKi0724-00 NWT-0:

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3,57,i25 Patented Dec. 4, T962 PRQDUCTIQN @F HTGEE TEMPERATURE, Hi HPERFQRMANCE, AND HTGH ENERGY HYD= CARBUN FUELS Arnold M. Leas, 893Beiiefonte Princess Road, Ashiund, Ky. Fitted Aug. 6, 1959, Ser. No.$33,664 it) (Iiainrs. (Cl. 2ti8-66) This invention relates to a processfor producing improved high temperature, high performance, and highenergy hydrocarbon fuels for turbojet, ramjet, and rocket engines. Morespecifically, it is concerned with making readily available largequantities of a wide variety of improved hydrocarbon fuels at relativelylow cost.

This application is a continuation-in-part of my prior applicationSerial No. 762,432, filed September 22, 1958, now abandoned.

The need for improved hydrocarbon fuels for aircraft is evident uponconsideration of their increased speed, increased range, and flight athigher altitudes. For an aircraft to fly at increased speed, thehydrocarbon fuel must display increased thermal stability, greaterreactivity, and improved combustion properties. For an aircraft to gofarther, the hydrocarbon fuel must possess higher combustionefliciencies under more stringent conditions together with greater heatcontent per unit weight and/or per unit volume. For an aircraft to gohigher, the hy drocarbon fuel must burn at lower pressure and must havehigher reactivity and lower vapor pressure to prevent prematurevaporization.

An object of this invention is the production of a high performancehydrocarbon fuel which possesses improved thermal stability. Thermalstability is defined as the resistance of a fuel to decomposition atelevated temperatures. Such decomposition results in the formation ofundesirable deposits in the fuel system and causes excessive vaporpressures. Obtaining better thermal stability is the greatest problemfacing aircraft propulsion today. At the operating temperaturesconcommitant higher ":ro pulsion speeds, the thermal stability of highperformance hydrocarbon fuels becomes critically important.

Another object of this invention is the provision of a high energyhydrocarbon fuel with low vapor pressure, which retains good flowcharacteristics at the very low temperatures encountered at highaltitudes, in order to maintain desirable handling characteristics andcomponent performance and to prevent center of gravity surge problems.

A more specific objective of this invention is the produc tion of analkylated naphthenic hydrocarbon of higher heat content thanconventional jet fuels. In the performance of liquid-fuel rockets, sucha compound has been found to possess desirable characteristics incomparison with the liquid boranes, the low density of which offsets thetheoretical increase in specific impulse.

A further objective of this invention is the production of alkylatednaphthenic hydrocarbon that is more resistant to nuclear radiation thanconventional jet fuels heretofore available. The alkylated syntheticnaphthenic hydrocarbons of this invention display much greaterresistance to gamma radiation than conventional jet fuels.

A still further objective of the invention is the provision of a processwherein various aromatic feedstocks of different boiling points and heatcontents, e.g. single rings (benzene), condensed rings (naphthalene ortetralin), isolated rings (biphenyl), along with olefinic gases, may becharged to yield products of specific distillation range as required forthe many weapon systems which travel at varying speeds. In order to makemany different types of hydrocarbon fuels economically, a producer needsan extremely flexible process to meet the urgent and rapidly changingdemands of the military and civilian industries. An example of theflexibility of this process 1s that its operating conditions can bechanged in order to alkylate one or more sidechains to the aromaticrings in order to control the distillation range of the end product.

Another objective of this invention is the provision of a chemicallypure product. This is effected by simple distillation whereby thereacted products which have a higher boiling point than the charge stockare removed as essentially pure aromatics. The heavy aromatic productmay be removed hot from the distillation tower bottoms and fed into thehydrogenation unit to produce a pure end product.

A specific objective of this invention is the production of hydrocarbonfuels which will pass both the Standard CRC Coker test and the ResearchCRC Coker test. These are tests which have been adopted to evaluate theperformance characteristics of fuels by subjecting them to conditionsgenerally simulating the adverse conditions which may exist in use.

The Standard CRC Coker test consists of pumping the fuel at ambienttemperature over an aluminum preheater tube into a second heater andthence into a standardized filter. The effluent from the filter iswater-cooled and passed into a receiver. The pressure drop through thefilter furnishes a measure of the quantity of the products of thermaldecomposition of the fuel retained by the filter, and hence is a measureof the fuels stability under heat. Deposits on the heat exchanger orpre-heater tube are also compared against standards to establish aso-called preheater rating. The Standard CRC Coker operates over a rangeof operating conditions as follows:

Pumping flow rate, lbs/hr 2-8.

Preheater temperature Ambient50() F. Filter temperature, F 400-600.Pumping pressure, p.s.i.g 150.

Duration of run, hrs 5-15.

No preheating chamber prior to run.

The Research CRC Coker test is designed for the testing of advancedhydrocarbon high performance fuels. It consists of pumping the fuel froma heated stain ess steel reservoir, which can be varied from ambient to300 F. temperature, to an aluminum or stainless steel preheater tubeinto a second heater and thence into a filter. The eflluent from thefilter is Water-cooled and passed into a receiver. The operatingconditions of the Research CRC Coker may be varied over a range asfollows:

Pumping flow rate, lbs/hr 2-10.

Preheater temperature Ambient800 F. Filter temperature, F 560-909.Pumping pressure, p.s.i.g 250.

Duration of run, hrs 5l5.

The heating reservoir is equipped with a mixer and can be blanketed withair and/ or inert gas in order to assimilate wing storage conditions.

The development of high performance hydrocarbon fuels has becomenecessary because all of the present conventional hydrocarbon fuels failto pass the Research Coker test. This invention permits producers tomake high performance hydrocarbon fuels that will pass the ResearchCoker test and also flight tests. For example, the Research and StandardCRC Coker preheater ratings range from 0 (best) to 8 (worst), and thefilter ratings range from 0 (best) to 25 inches (worst). Fuels may beproduced according to thi invention which will pass the Research CRCCoker test with a preheater rating of 3 maximum and a filter pressuredrop of 1.0 inch maximum.

A further obiect of this invention is the provision of a simple andeconomical process for producing from inexpensive petroleum chargestocks high temperature, high performance, and high energy hydrocarbonfuels which are more resistant to nuclear radiation, which process,because of the mild operating conditions utilized, is adapted to bepracticed with relatively simple and inexpensive equipment. The processfacilities can, in fact, be made readily available by a simpleconversion of conventional petroleum refinery facilities.

The process of this invention consists principally in the reaction of acatalytic reformate which contains benzene, toluene, and heavieraromatic boiling in the range from 150 to 450 F., with a light olefinichydrocarbon which is preferably ethylene, propylene, and butylene, or amixture thereof, using phosphoric acid catalyst, solid or liquid, in thepresence of hydrogen to efiect reaction at moderate temperature, forexample, 150 450 F., and at moderate pressure, for example 15030Op.s.i.g. to produce an essentially pure high boiling aromatichydrocarbon, and then hydrogenating the high boiling aromatic compoundsto form a naphthenic end product. A further aspect of the invention is anovel treatment of this naphthenic product with hot and cold clay toimprove the thermal stability of the end product, as subsequentlydescribed.

The reaction preferably is conducted in the presence of hydrogen, someof which may be recycled to the reaction zone in order to minimizecarbon deposition and to improve catalyst activity. It has beendiscovered that the presence of hydrogen at the site of the reaction,obtained by injection of hydrogen if necessary, contributes veryadvantageously to the maintenance of high catalyst activity and catalystlife, particularly in the charging of heavier feed stock, and alsoreduces carbon deposition and suppresses undesirable side reactions.

In order to maintain proper hydration of the phosphoric acid catalyst,water, alcohol, or another suitable source of hydroxyl groups may beadded to the alkylation zone. The mild operating conditions are madepractical by operating at low space velocity. The low operatingtemperature and pressure enable the use of standard carbon-steelequipment which is readily available in most petroleum refineries.

The low boiling hydrocarbons or unreacted components may be recycled toobtain high yields of essentially pure high boiling aromatics. These areseparated by simple fractionation and constitute a charging stock for asecond step wherein the high boiling aromatics are hydrogenated by meansof a suitable hydrogenation catalyst, e.g., platinum or nickel, undermild operating conditions (300600 F. and 3004000 p.s.i.g.).

A novel feature of this invention resides in the discovery that thephosphoric acid catalyst functions to promote the alkylation of aromaticby olefinic components present at the site of reaction andsimultaneously promotes dehydrogenation in the conversion of parafiincomponents to olefins which then alkylate the aromatics and/ or cyclizeolefins to additional aromatics which further alkylate. From presentevidence it appears feasible under various plant operating conditions torecycle all of the low boiling hydrocarbons to the alkylatingdehydrocyclization catalyst to permit almost complete conversion of thecharge stock to high boiling aromatics suitable for hydrogenation to thedesired product. However, for given plant facilities, increasedquantities of the desired high energy fuel product can be obtained bydiverting a portion of the recycle stock for use as valuable by-productmaterial suitable for gasoline blending or as petrochemical chargestock. Material balances indicate that sufficient dehydrogenation occursin the alkylation step to provide a portion of the hydrogen required tosaturate the heavy aromatics in the second or hydrogenation step of theprocess. Up to approximately 25% motor alkylate and/or iso-octaneeconomically may be included in the reformate charge to provideiso-octyl benzene which can i also be subsequently saturated withhydrogen to increase the heating value of the finished product.

The process of this invention also includes incorporating biphenyl andother polycyclic hydrocarbons which can be alkylated with ethyleneand/or propylene and/ or butylene to produce products which can befurther hydrogenated to increase the heating value and density of thefinished product. Thus, products of this invention are essentially purealkyl naphthenic hydrocarbons, principally dimeric and trimeric, whichhave unusually good thermal stability properties, combined with highenergy content. The proecss possesses sufficient flexibility to enablespecial end products to be obtained by variations in the feed stock inorder to satisfy specific or specialty requiremcnts.

The following examples are given to indicate results obtainable by theuse of the present process, although they are not intended to limit thescope of the invention to exact correspondence herewith.

EXAMPLE 1 A liquid charge consisting of by liquid volume of catalyticreformate (boiling point l40250 F.) and 25% heart cut alkylate (boilingpoint 140-250 F.) with sufficient propylene is charged to the phosphoricacid catalyst reactor to produce a product which on fractionation yields35% heavy aromatics (boiling point approximately 375-600 F.) and 65% ofa product boiling below 375 F. which may be diverted or recycled; ifrecycled, this fraction on the second and third pass yields comparablequantities of the 375 F. residue without impairing the desirableproperties of the fraction. When the 375 F. residue heavy aromaticfraction is saturated with hydrogen, it yields a product having an APIgravity of about 40, boiling range of 375-600 F, freezing! point ofbelow F., viscosity at 30 F. of 20 centistokes, net heating value of13,700 B.t.u./lb. or 128,282 B.t.u./gal., and a CRC Research Cokerrating of= substantially less than 1 inch Hg filter pressure drop and amaximum preheater rating of No. 2 under the following conditions:

Pre-test treatment consisted of heating and agitating the fuel in thepresence of air at 300 F. for 5 hours. From the foregoing data, it willbe seen that the present invention provides a process for manufacturinghigh performance hydrocarbon fuels capable of passing the Research CRCCoker Test, which convenional jet fuels completely fail.

According to the Standard CRC Coker test procedure previouslyidentified, air is not present during test preheating or thereafter.However, air is present in wing tanks of aircraft during high speedflight, and skin friction causes appreciable rise in the temperature ofthe fuel therein, which may continue over prolonged flight periods. Thebest high energy hydrocarbon fuels presently available, when exposed toheat and air under such conditions, give Research CRC Coker ratingswhich are considerably less desirable than the coker ratings furnishedby the same fuels not subjected to the heat and air environment. Incontrast, fuels prepared in accordance with the present inventiondisplay the same Re search CRC Coker rating whether preheated accordingto the test in the absence of air or preliminarily exposed e3 to air ata temperature of 300 F. for hours prior to preheating and testingaccording to the standard procedure. This shows the remarkable thermalstability of the fuels under conditions which are even more adverse thanthose in the Standard CRC Coker procedure.

EXAMPLE 2 Using the same charge stock as in Example 1 plus by weight ofbiphenyl added thereto, a finished fuel product is produced havingsimilar properties and Research CRC Coker rating to those shown inExample 1 with the exception that the API gravity is 35 and the netheating value is increased to 18,750 B.t.u./lb. and 132,675 B.t.u./gal.

EXAMPLE 3 A liquid charge consisting of catalytic reformate (boilingpoint 140-250 F.) with sufficient propylene is charged to the phosphoricacid catalyst reaction to produce a product which on fractionationyields 23% heavy aromatics (boiling point 375600 F.) and 77% of aproduct boiling below 375 F. which may be diverted or recycled; ifrecycled, this fraction on the second and third pass yields comparablequantities of the 375 F. residue without impairing the desirableproperties of the fraction. When the 375 F. residue heavy aromaticfraction is saturated with hydrogen, it yields a product having an APIgravity of about 40, boiling range of 375 600 F., freezing point ofbelow 9'0 F., viscosity at 30 F. of centistokes, net heating value of18,650 B.t.u./lb. or 128,125 B.t.u./gal., and a Research CRC Cokerrating similar to that of Example 1.

.. EXAMPLE 4 A liquid charge consisting of heavy catalytic reformate(boiling point 250-450 F.) with sufificient propylene is .charged to thephosphoric acid catalyst reactor in the presence of hydrogen to producea product which on fractionation yields 65% high purity aromatics(boiling point approximately 415650 F.) and 35% of a product boilingbelow 415 P. which may be diverted or recycled; if recycled, thisfraction on the second and third pass yields comparable quantities ofthe 415 F. residue without impairing the desirable properties of thefraction. When the 415 F. residue heavy aromatic fraction is saturatedwith hydrogen, it yields a product having an API gravity of about 31.5",boiling range of 390-625 F., freezing point of below -100 F., viscosityat 30 F. of 14.5 centistokes, net heating value of 18,420 B.t.u./lb. or133,140 B.t.u./gal., and a similar Research CRC Coker rating as shown inExample 1 The product from this charge stock is primarily a mixture ofalkylated monocyclic and alkylated bicyclic naphthenes.

EXAMPLE 5 The pure heavy aromatic hydrocarbon from the reactor unit asillustrated in Example 1 can be blended with naphthalene and thencharged to the hydrogenation unit to make a product that is similar tothe finished product shown in Example 4. Likewise tetralin can replacethe naphthalene as charge to the hydrogenation unit along with the pureheavy aromatic in Example 1 to make a product similar to that in Example4.

EXAMPLE 6 Following is an example of the improvement in thermalstability which is conferred upon a fuel product by hot and cold claytreatment following hydrogenation.

Naphthalene and/0r tetralin can be charged directly to the hydrogenationunit to produce high quality decalin with an API gravity of about 301,boiling range of 350390 E, freezing point of 40 F., viscosity at 30 F.of 11.6 centistokes, net heating value of 18,412

6 B.t,n./lb. or 134,242 B.t.u./gal., and a Research CRC Coker rating asshown below.

Pumping flow rate, lbs/hr 6 Preheater temperature, F 550 Filtertemperature, F 650 Pumping pressure, p.s.i.g 250 Duration of run, hrs 5Pretest treatment consists of heating and agitating in the presence ofair at 300 F. for 5 hours.

Decaiin is limited in its application because of its high volatility,relatively high freeze point, and high price. The distillation range ofdecalin is 360 390 F. whereas many of the higher speed weapon systemsrequire hydrocarbon fuels that have a distillation range between 375-600 P. such as illustrated in Examples 1 through 5. Likewise the priceof decalin is approximately ten times the cost of products described inExamples 1 and 3. The availability of decalin is very limited comparedto the products described in Examples 1 through 5.

In aircraft armed with nuclear projectiles the fuel for the aircraftinevitably is or will be subjected to gamma radiation. Such radiationhas been found to exert serious decomposing effects upon varioushydrocarbons and in particular upon JP4, JP-5, and JP-6 fuels whichconstitute the fuels now commonly used in such aircraft. The adverseeffect of radiation is indicated by decrease of Research CRC Cokerrating of the fuel. However, exposure to gamma radiation of the fuels inthe present invention has been found to have no significant effect upontheir coker rating.

One method suitable for the practice of the process of this invention isillustrated schematically in the accompanying drawing. Olefins from acharge component comprising ethylene, butylene, and propylene ormixtures thereof, proportioned in relation to the end product desired,plus whatever inert gases such as pentane, butane, ethane, and propanethat may be present therein, enter the system through line 1. Wherethese gases are supplied from cracking processes, hydrogen also normallywill be present; if not, hydrogen as required in the practice of theprocess is supplied as later described. The gases entering the systemthrough line 1 are first prepared for use by treating them to removehydrogen sulfide and ammonia as is indicated generally at 2. This typeof gas purification is conventional and therefore is not described herein detail.

From the preparation step 2 the gases are delivered by a compressor 3 togas charge line 4 which is valved as at 5. A portion of the compressordischarge is preferably passed through line 6 into an absorber 7.

The parafiinic liquid feed components, i.e., C catalytic reformate andsuch alkylate as iso-octane which it is desired to employ, enter thesystem through line 8 and pass into a depentanizer 9 through whichentrained pentane is removed from the charge and discharged through line10. The balance of the liquid charge passes through line 11 to asplitting tower 12 which is operated to separate heavy or high boilingreformate and alkylate from the desired lighter fractions of thesecomponents. The heavy product is discharged from the system through line1.3 and passes to storage for use as a gasoline blend ing additive orfor other desired uses, while the light reformate and alkylate enter thereaction system through a pump 14 which discharges into feed line 15.However, a portion of the liquid feed is diverted through the line 16into the absorber '7 wherein it absorbs components of the gas feed andrich oil from the absorber, re-enters the feed stream through line 17,the flow rate through the absorber being adjusted by means of valve 18.Feed gases which are insoluble in the absorber liquid, such as methaneand nitrogen, are ejected from the system through line 19. Some excesshydrogen is lost in this procedure, but a typical refinery gas containshydrogen substantially in excess of the amount required in the practiceof the present process, so this loss is of no immediate consequence.

The combined liquid and gas charge in line now passes through a heater20 and then into reactor 21.

In the system illustrated, the reactor contains a fixed bed ofphosphoric acid as a catalyst. In the preferred operation the phosphoricacid is of 60-70% strength and is disposed upon a carrier such assilicon dioxide or kieselguhr. The water content of the catalystpreferably is approximately 12-15%; for convenience, the catalyst may berepresented typically as SiO -P O -H O. Loss of water from the catalystas the reaction proceeds is made up by addition of water or alcoholintroduced suitably into the line 15. The use of alcohol in place ofWater generally permits better control of the OH addition rate.

Within the reactor at number of diflierent reactions take place as issubsequently discussed. Some of these are exothermic and someendothermic, by reason of which it is generally unnecessary to providefor substantial removal of heat from the reactor. If necessary,temperature reduction readily may be obtained through quenching effectby diverting the feed stream through the heater 20 or by addition of arecycle stream as is discussed at a later point in the specification.

When the gas charge is deficient in hydrogen, hydrogen may be supplieddirectly to the reactor 21 as indicated by the dotted line 22.

Mixed products of the reaction leave the reactor through line 23 andpass to a first fractionator 24 wherein light aromatic hydrocarbons suchas ethyl benzene are removed. The bottoms product of this fractionatoris passed through line 25 to a second fractionator 26 wherein heavieraromatic hydrocarbons such as cumene are removed. The bottoms product ofthe second fractionator, as flowing in line 35, now constitutes anessentially pure aromatic hydrocarbon which, under the preferredtemperature of the second fractionator, boils at a temperature ofapproximately 375600 F.

Each of the fractionators 24 and 26 preferably is equipped for refluxoperation. Thus, in unit 24, the overhead product passes from line 27through a condenser 28 to a receiver 29 from which the reflux isreturned to the fractionating column through line 30. Gas liberated fromthe overhead fraction is discharged from the receiver through line 31 asa fuel gas. The reflux system in the second fractionator 26 is the same,but in this case no vent gas line is required since non-condensiblegases are stripped from the product in the first fractionatingoperation.

In the practice of the process the low boiling and high boiling aromatichydrocarbons removed at fractionators 24 and 26 either may be used aspetrochemical feed stocks or may be used for blending with gasoline.However, an important economic advantage in the practice of the presentinvention is provided by the utilization of these fractions as recyclecharge stock to the reactor. For this purpose the components aswithdrawn from the fractionators through lines 32 and 33 may be mixedand recycled to the reactor 21 through line 34. This recycle streamprovides convenient means for controlling the temperature in the reactorif necessary.

In the second phase of the production of thermally stable, high energyliquid fuels according to the present invention, the aromatichydrocarbons flowing in line 35 are hydrogenated for conversion of thearomatic hydrocarbons to naphthenes. This operation is conducted at thehydrogenator 37. The charge, before entering the hydrogenator, passesthrough a heater as through which the temperature may be controlled.Hydrogenation is conducted in the presence of a suitable hydrogenationcatalyst such as platinum or nickel on a suitable carrier such asaluminum oxide. For hydrogen supply to the hydrogenator, reformeroif-gas may be used, in which event the gas is treated to effect removalof hydrogen sulfide by conventional means as indicated generally at 39.

The naphthene stream, discharged from hydrogenator 37 in line 42, passesthrough a condenser 43 into a liquid gas separator 44. Hydrogen gasliberated at the separator 44 is recycled by means of a compressor 41and return line 40 while the hydrogenated liquid product is passed fromthe receiver 44 through a line 45 into a stripper 46 where residualhydrogen or inert gases are removed. These are discharged through line47, and the end product is discharged through line 48.

Next the liquid product discharged from stripper 46 is preferablysubjected to a hot clay treatment followed by a cold clay treatment.This treatment has been found efiective to remove small traces ofundesirable organometallic compounds containing copper, lead, andarsenic which otherwise adversely aflect heat stability. In addition,however, it has been discovered that even small amounts of olefiniccompounds present in fuel impair its Coker Rating, and that the hot claytreatment followed by cold clay treatment is effective to improve theCoker; rating, apparently by effecting the removal of such com-f pounds.Such improvement is indicated, typically, in the data accompanyingExample 6. Thus, the liquid product from the stripper 46 is dischargedthrough line 48 to a hot clay reactor 49 which is charged with asuitable clay such as bauxite and which is operated at a temperature ofapproximately 300650 F., preferably 600 F. Flow rate is adjusted to aspace velocity of approximately one, which allows ample time ofresidence to permit polymerization of unstable hydrocarbons such asmonoand diolefins to occur. From the hot clay reactor the liquid productis discharged through line 50 and through a cooler 51 to a cold claytower 52 similarly charged with a suitable clay such as bauxite. Thecold clay treatment is effective to filter the polymerized hydrocarbonsand metal compounds from the stream. The end product is discharged fromthe system through line 54 to storage. This finished end product is thehigh temperature fuel possessing high thermal stability, resistance toradiation, high performance properties, together with higher energy thanother presently known hydrocarbon ue s.

As previously noted, the invention is practiced at realtively nominaltemperature and pressure conditions, which permits carbon steel vesselsand piping to be used at low cost. In the reactor the preferredtemperature of operation is approximately 300400 F. and the pressureapproximately 200400 p.s.i.g. The low cost of the carbon steelconstruction permits a reactor to be employed which is sufiicientlylarge to enable a low space/hourly rate velocity to be maintained. Forexample, in the physical operation the space/hourly rate velocity may be.05 to 1.0, and preferably approximately 0.1 (gallons combined feed perhour per pound of catalyst).

It will be understood that the proportion of gas feed to liquid feed aswell as the chemical constitution of each will affect the properties ofthe end product. In general, the proportions preferably are adjusted sothat 2 to 3 mole of ethylene, propylene, or butylene, or mixturesthereof, are available for each mol of benzene in the liquid feed, andhydrogen is maintained in quantity to furnish approximately one-1211fmol of hydrogen per mol of benzene in the liquid feed. Saturation of thearomatic hydrocarbons at the hydrogenator 37 preferably is conducted ata temperature of approximately 450 F.

To efiect removal of light aromatic hydrocarbons, the first fractionatormay be operated at a temperature of approximately 300 F. atapproximately 50 p.s.i.g., the desired drop ni pressure being obtainedby any suitable means such as a pressure rcducing valve (not shown) inline 23. The second fractionator 26 is operated at a temperature ofapproximately 450 F. at approximately atmospheric pressure to yield abottoms product having an initial boiling point of approximately 375 F.However where other specialized end products are desired, fractionator26 may be operated to furnish a bottoms product having an initialboiling point above or below 375 F. as described. The preferred endproducts are disclosed herein in the sense that such materials show thebest balance of physical characteristics, taking vapor pressure, flashpoint, low temperature, viscosity, and freezing point into account inrelation to their effect upon fuel performance in aircraft or missileengines.

The exact reactions which occur in the reactor 21 are not fullyunderstood at present. Primarily, it is believed that alkylation occurssimultaneously or conjointly with dehydrogenation and cyclization. Forexample, it is probable that hexane in the C reformate becomesdehydrogenated to hexene or benzene which, in turn, acquires ethyl,methyl, or propyl radicals. It may also be that hexene alkylates withother benzene molecules entering via the feed. Similar reactions mayoccur when isooctane forms a part of the liquid feed, and similarreactions also may occur where polycyclic compounds are present in ordeliberately added to the liquid feed, such as biphenyl. In fact, byaddition of biphenyl to the reaction site, such as by introductionthereof into line 15 at a point just ahead of the reactor, the heatcontent of the end product in terms of B.t.u.s per gallon may bematerially increased, for example, from 128,282 when biphenyl is absentto 132,675 when biphenyl is added to the extent of approximately 10% byweight of the liquid feed component. In place of biphenyl, fused ringaromatic compounds such as naphthalene may be added to the extent orapproximately 10% by weight of the liquid feed component. Addition ofgreater quantities of either of such types of polycyclic aromaticcompound is of diminishing advantageousness. Also, as previously noted,while the use of a liquid hydrocarbon feed consisting entirely of Creformate furnishes an end product of high heat content, the heatcontent of the end product is increased by incorporation of iso-octaneor alkylates containing the same. Thus when iso-octane alkylateconstitutes 25% by volume of the liquid feed, the heat content isincreased approximately 50 B.t.u./lb. over what it would be if thiscomponent were omitted from the feed. In general, because of diminishingreturns, it appears to be economically undesirable to add alkylate to anextent substantially exceeding 25% by volume of the liquid feed.

The invention has been disclosed particularly in relation to the use ofpetroleum reformate as the source material for benzene and toluene onaccount of the economies which the use of reformate provides, but itwill be understood that benzene and toluene in admixture producedseparately from other petroleum refining methods or from coal tar may beused and that the term reformate as used herein is intended to includesuch alternative source materials.

From the foregoing description of the principles upon which theinvention is based and the detailed descriptions of typical procedures,those skilled in the art readily will comprehend the variations to whichthe invention is susceptible. By the present process products havingunexpectedly high thermal stability characteristics are obtained bymixed reactions conducted simultaneously under mild operating conditionsand at low cost of operation. The yield of the desired high performancehydrocarbon end products is not only good but in turn is accompanied bythe production of by-products which are adapted to be recycled or soldat favorable prices for other purposes.

Having described my invention, I claim:

1. A process for producing a substantially pure high boiling alkylnaphthenic fuel for use in jet aircraft and missile propulsion whichfuel is characterized by an energy content in excess of 18,400 B.t.u.per pound, thermal stability, and resistance to gamma radiation, saidprocess comprising, reacting petroleum reformate and light olefinichydrocarbons in the range of ethylene, propylene and butylene inadmixture with a source of hydroxyl groups, said source being selectedfrom the class consisting of water and alcohol, and hydrogen at atemperature of approximately 150-450" F. in the presence of a phosphoricacid catalyst and at a space velocity in the range of about 0.05 to 1.0to produce an intermediate product containing highly alkylated benzenecompounds, fractionating a high boiling portion of said intermediateproduct which portion primarily comprises alkyl benzene compoundsboiling above about 375 F. and below about 600 F., and hydrogenatingsaid high boiling portion.

2. A process in accordance with claim 1 in which said reformate has aninitial boiling point above approximately F. and an end boiling pointbelow approximately 450 F.

3. A process in accordance with claim 1 in which said reformate boils inthe range of approximately 250-450 F.

4. A process in accordance with claim 1 in which a minor portion ofpolycyclic hydrocarbons are added to said reformate and are reacted withsaid light olefinic hydrocarbons in the presence of said catalyst.

5. A process in accordance with claim 1 in which following saidhydrogenation, said high boiling portion is contacted with clay at atemperature of about 300-350 F. to effect the polymerization of unstablecompounds therein, and in which the polymerized compounds are thenfiltered from said high boiling portion.

6. A process in accordance with claim 1 in which following saidhydrogenation, said high boiling portion is treated with hot clay at atemperature of approximately 300350 F. and then with cold clay to effectpolymerization and removal of unstable hydrocarbons therefrom.

7. A process in accordance with claim 1 in which a fraction of saidintermediate product boiling below said high boiling portion is recycledinto contact with said catalyst to efifect conversion of at least aportion of the recycled fraction into high boiling highly alkylatedbenzene compounds.

8. A process for producing a substantially pure high boiling naphthenicfuel for use in jet aircraft and missile propulsion which fuel ischaracterized by an energy content in excess of 18,400 B.t.u. per pound,thermal stability, and resistance to gammaradiation, said processcomprising, reacting petroleum reformate and light olefinic hydro carbonin the range of ethylene, propylene and butylene in admixture with asource of hydroxyl groups, said source being selected from the classconsisting of water and alcohol, and hydrogen in the presence of aphosphoric acid catalyst at a space velocity in the range of about 0.05to 1.0 and at a temperature of approximately 450 F. to produce anintermediate product containing highly alkylated benzene compounds,fractionating a high boiling portion of said intermediate product havingan initial boiling point above about 375 F. and an end boiling pointbelow about 600 F. and which comprises substantially pure high boilingalkyl benzenes, adding a fused ring compound to said high boilingportion, and hydrogenating the resultant mixture.

9. A process in accordance with claim 8 in which said fused ringcompound comprises naphthalene.

10. A process for producing a substantially pure high boiling alkylnaphthenic fuel for use in jet aircraft and missile propulsion whichfuel is characterized by its high energy content, thermal stability, andresistance to gamma radiation, said process comprising, contactingadmixed petroleum reformate boiling in the range of approximately 140250F. and light olefinic hydrocarbons in the range of ethylene, propyleneand butylene with a phosphoric acid catalyst at a temperature ofapproximately 300400 F, a pressure of approximately 200-400 p.s.i.g.,and a space velocity of approximately 0.1 in the presence of water andhydrogen to produce an intermediate product containing alkyl benzenecompounds, fractionating a portion of said intermediate product boilingin the range of approximately 375600 F. and comprising substantiallypure alkyl benzenes, and hydrogenating said portion.

References Cited in the file of this patent UNITED STATES PATENTS RosenMay 28, 1940 Corson et a1. June 30, 1942 Mayer Nov. 30, 1943 DeanesleyJuly 20, 1954 Love et a1 Jan. 17, 1956 Gluesenkamp et al. Oct. 9, 1956Hemminger Nov. 27, 1956 Skinner et al. Jan. 8, 1957 Gluesenkamp et a1Oct. 27, 1959 Schuman Dec. 8, 1959 Wankat et al. June 7, 1960 FOREIGNPATENTS Canada July 5, 1955 UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Patent No. 3.067 126 December 4; 1962 Arnold M. Leas It ishereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

In the grant, lines 1 to 3, for "Arnold M. Leas, of Ashland, Kentuckyread Arnold M. Leas of Ashland Kentucky, assignor to Ashland Oil 81Refining Company of Ashland Kentucky a corporation of Kentucky line 12for "Arnold M. Leas his heirs" read Ashland Oil 81 Refining Company itssuccessors in the heading to the printed specification,

lines 5 and 6, for "Arnold M. Leas 803 Bellefonte Princess Road Ashland,Ky." read Arnold M. Leas Ashland, Ky.

assignor to Ashland Oil 81 Refining Company Ashland Kyo V a corporationof Kentucky column 10, lines 60 and 61, for

"hydrocarbon" read hydrocarbons Signed and sealed this llth day of June1963.

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents

1. A PROCESS FOR PRODUCING A SUBSTANTIALLY PURE HIGH BOILING ALKYLNAPHTHENIC FUEL FOR USE IN JET AIRCRAFT AND MISSIBLE PROPULSION WHICHFUEL IS CHARACTERIZED BY AN ENERGY CONTENT IN EXCESS OF 18,400 B.T.U.PER POUND, THERMAL STABILITY, AND RESISTANCE TO GAMMA RADIATION, SAIDPROCESS COMPRISING, REACTING PETROLEUM REFORMATE AND LIGHT OLEFINICHYDROCARBONS IN THE RANGE OF ETHYLENE, PROPYLENE AND BUTYLENE INADMIXTURE WITH A SOURCE OF HYDROXYL GROUPS, SAID SOURCE BEING SELECTEDFROM THE CLASS CONSISTING OF WATER AND ALCOHOL, AND HYDROGEN AT ATEMPERATURE OF APPROXIMATELY 150-450*F. IN THE PRESENCE OF A PHOSPHORICACID CATALYST AND AT A SPACE VELOCITY IN THE RANGE OF ABOUT 0.05 TO 1.0TO PRODUCE AN INTERMEDIATE PRODUCT CONTAINING HIGHLY ALKYLATED BENZENECOMPOUNDS, FRACTION-